A communication service for transmitting data of a text message in a store-and-forward system from a calling terminal device in a source network, which is a network where the calling terminal device is located, to a receiving terminal device in a destination network, which is a network where the receiving terminal device is located, through one or more communication relay apparatuses of other networks and providers is already carried out in multiple countries as one of known communication services called, for example, short message service.
Primarily, in such an existing short message service, the connection of a line is permitted in a case where a communication carrier of a subscriber on the calling side and a communication carrier of a subscriber on the receiving side have made agreements. In a case where they have not made agreements, it is necessary to determine the acceptability of the connection and to control the connection not to be permitted.
There has been proposed a technique for determining the acceptability of connection and controlling the connection according to the result of the determination similar to the technique described above as a technique for determining the suitability of the connection of a telephone call, particularly in relation to whether or not the subscriber can be appropriately charged (for example, see Patent Document 1).
In the proposal described in Patent Document 1, when a call response signal transmitted from a destination network is received in a connection procedure of a telephone call, a selected relay carrier checks whether the communication carrier of the destination network is registered in an carrier information list for receiving calls, including the communication carriers of the destination network that have made agreements with the selected relay carrier, based on the carrier information for receiving calls for identifying the communication carrier of the destination network included in the call response signal. The selected relay carrier denies the connection if the carrier is not registered, but allows the connection if the carrier is registered.
The proposal described in Patent Document 1 is not a technique particularly provided for a short message service. Meanwhile, there has already been proposed a technique for handling a problem in the determination of the acceptability of connection in the short message service.
More specifically, there have been proposed an interconnection contract determination system and an apparatus such that in a case where a calling terminal and a receiving terminal subscribe to different carriers (communication carriers), and only in a case where the different carriers have made a short message service interconnection contract, short messages can be transferred between the calling terminal and the receiving terminal (for example, see Patent Document 2).
The proposal of Patent Document 2 discloses the necessity of control in which a mobile switching center located in an area that has received a forward request of a short message from a calling terminal determines the presence of an SMS (Short Message Service) interconnection contract between the contract carriers of the calling terminal and the receiving terminal. The mobile switching center forwards the received short message to a short message distribution center (SMSC: Short Message Service Center) only when is the presence of such a contract is confirmed. Furthermore, in order to perform the above control in a appropriate manner, in the disclosure, the mobile switching center in the area, determines whether the contract carrier of the receiving communication terminal has signed an interconnection contract with the carrier of the source network based on information of an SMS interconnection contract carrier list held in advance by the mobile switching center in the area as a technical level already at the proposal.
Particularly, in the proposal of Patent Document 2, the mobile switching center in the area is allowed to determine in an accurate fashion the carrier subscribed by the receiving communication terminal based on subscriber identification information even if the telephone number of the receiving communication terminal is not changed by number portability. In the disclosure, the determination of the short message service interconnection contract can be accurately performed based on the accurately determined carrier.